Butene-1/ethylene copolymer

ABSTRACT

A 1-butene/ethylene copolymer having a content of ethylene derived units from 0.1% to 5% by weight in which an ethylene content in the polymer (C 2 ) and a melting point of the polymer (Tm) meet the following relation:
 
Tm&lt;−0.3283C 2   3 +4.7184C 2   2 −22.454C 2 +114.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 10/479,328,filed Dec. 2, 2003 now U.S. Pat. No. 7,074,864, which is a nationalphase filing under 35 U.S.C. §371 of International Patent ApplicationNo. PCT/EP02/06575, filed on Jun. 11, 2002, which claims priority toEuropean Patent Application 01202263.8 filed on Jun. 12, 2001. Theentire contents of application Ser. No. 10/479,328, International PatentApplication No. PCT/EP02/06575 and European Patent Application01202263.8, each as filed, are incorporated herein by reference.

The present invention relates to a process for polymerizing 1-butene byusing a substituted bis cyclopentadienyl bridged metallocene compound.1-butene polymers are well known in the art. In view of their goodproperties in terms of pressure resistance, creep resistance, and impactstrength they have a lot of uses such as the manufacture of pipes to beused in the metal pipe replacement, easy-open packaging and films. The1-butene (co)polymers are generally prepared by polymerizing 1-butene inthe presence of TiCl₃ based catalysts components together withdiethylaluminum chloride (DEAC) as cocatalyst. In some cases diethylaluminum iodide (DEAI) is also used in mixtures with DEAC. The polymersobtained, however, generally do not show satisfactory mechanicalproperties. Furthermore, in view of the low yields obtainable with theTiCl₃ based catalysts, the 1-butene polymers prepared with thesecatalysts have a high content of catalyst residues (generally more than300 ppm of Ti) which lowers the properties of the polymers making itnecessary a deashing step. 1-butene (co)polymers can also be obtained bypolymerizing the monomers in the presence of a stereospecific catalystcomprising (A) a solid component comprising a Ti compound and anelectron-donor compound supported on MgCl₂; (B) an alkylaluminumcompound and, optionally, (C) an external electron-donor compound. Aprocess of this type is disclosed in EP-A-172961 and more recently inWO99/45043. In Macromolecules 1995, 28, 1739-1749rac-dimethylsilylbis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichlorideand methylaluminoxane have been used for polymerizing 1-butene, even ifthe yield of the process is not indicated the molecular weight of thepolymer (Mn) is very low. Recently metallocene compounds have been usedfor producing 1-butene polymers. In Macromol. Rapid Commun. 18, 581-589(1997) rac andmeso-[dimethylsilylenebis(2,3,5-trimethyl-cyclopentadienyl)]zirconiumdichloride have been used for the polymerization of 1-butene, the yieldsof the process and the molecular weight of the obtained polymers arerather low. More recently in Macromolecules 2000, 33, 1955-1956Me₂Si(2-Me-4,5-BzoInd)₂ZrCl₂, Me₂Si(2-Me-4-PhInd)₂ZrCl₂ andMe₂Si(Ind)₂ZrCl₂ have been tested in the polymerization of 1-butene.Even if the molecular weights of the polymers appear to be quite high,the activities of these catalysts are low as shown in the comparativeexamples of the present application. A new process that permits toobtain 1-butene polymer with high molecular weight and in high yield istherefore desirable. An object of the present invention is a process forpolymerizing 1-butene comprising the step of contacting underpolymerization conditions 1-butene and optionally from 0 to 20% by mol,preferably from 0 to 10% by mol of ethylene, propylene and/or an alphaolefin of formula CH₂═CHZ wherein Z is a C₃-C₁₀ alkyl group, in thepresence of a catalyst system obtainable by contacting:

a) a racemic or racemic-like bridged metallocene compound of formula (I)

-   -   wherein    -   R¹, same or different, is hydrogen, a linear or branched        saturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,        C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical,        optionally containing heteroatoms belonging to groups 13-17 of        the Periodic Table of the Elements; preferably R¹ is hydrogen or        a C₁-C₂₀-alkyl radical, more preferably R¹ is hydrogen or        methyl.    -   A, same or different, is a carbon atom, a germanium atom or a        silicon atom; with the proviso that, when m is 1, A is different        from a carbon atom; preferably A is a silicon atom;    -   m is 1 or 2, preferably m is 1;    -   R², same or different, is hydrogen, or a linear or branched        saturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,        C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical,        optionally containing heteroatoms belonging to groups 13-17 of        the Periodic Table of the Elements; preferably R² is hydrogen, a        C₁-C₂₀-alkyl or a C₆-C₂₀-aryl; more preferably R² is hydrogen,        methyl or phenyl;    -   more preferably the bridge (R² ₂A)_(m) is Si(CH₃)₂, SiPh₂,        CH₂CH₂;    -   M is a transition metal atom selected from those belonging to        group 4 of the Periodic Table of the Elements (IUPAC version);        preferably M is zirconium or hafnium, more preferably M is        zirconium;    -   X, same or different, is a hydrogen atom, a halogen atom, or a        R, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ group, wherein R is a        linear or branched, saturated or unsaturated C₁-C₂₀ alkyl,        C₃-C₂₀ cycloalkyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl or C₇-C₂₀        arylalkyl radical, optionally containing heteroatoms belonging        to groups 13-17 of the Periodic Table of the Elements; or two X        can optionally form a substituted or unsubstituted butadienyl        radical or a OR¹¹O group wherein R¹¹ is a divalent radical        selected from C₁-C₂₀ alkylidene, C₆-C₄₀ arylidene, C₇-C₄₀        alkylarylidene and C₇-C₄₀ arylalkylidene radicals; preferably X        is a hydrogen atom, a halogen atom or a R group; more preferably        X is chlorine or a methyl radical;    -   wherein the R substituents are selected from linear or branched,        saturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,        C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical,        optionally containing heteroatoms belonging to groups 13 or        15-17 of the Periodic Table of the Elements; preferably X is        hydrogen, a halogen atom, a R or OR group; more preferably X is        hydrogen, chlorine or methyl;    -   L, same or different, is a moiety of formula (Ia), (IIb), or        (IIc):

-   -   wherein    -   in the moiety of formula (IIa) T bonds to the cyclopentadienyl        group in position 5;    -   in the moiety of formula (IIb) N bonds to the cyclopentadienyl        group in position 4;    -   in the moiety of formula (IIc) the carbon atom marked with the        symbol * bonds to the cyclopentadienyl group in position 4;    -   T is an oxygen (O) atom, a sulphur (S) atom or a CH₂ group;        preferably T is sulphur;    -   R³ is hydrogen or a linear or branched, saturated or unsaturated        C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl,        C₇-C₂₀-arylalkyl radical, optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;    -   R⁴ is a linear or branched saturated or unsaturated        C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl,        C₇-C₂₀-arylalkyl radical, optionally containing heteroatoms        belonging to groups 13-17 of the Periodic Table of the Elements;    -   preferably, R³ is hydrogen or a C₁-C₂₀-alkyl radical; more        preferably R³ is methyl;    -   preferably, R⁴ is a C₁-C₂₀-alkyl radical; more preferably R⁴ is        methyl;    -   R⁵, R⁶, R⁷, R⁸ and R⁹, same or different, are selected from the        group consisting of hydrogen, a linear or branched saturated or        unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl,        C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical, optionally        containing heteroatoms belonging to groups 13-17 of the Periodic        Table of the Elements, or two adjacent groups can form together        a saturated or unsaturated condensed 5 or 6 membered ring        optionally containing heteroatoms belonging to groups 13-16 of        the Periodic Table of the Elements; Preferably R⁷ is hydrogen or        methyl; preferably R⁵, R⁶, R⁸ and R⁹ are hydrogen.        b) an alumoxane or a compound able to form an alkylmetallocene        cation; and        c) optionally an organo aluminum compound.

Preferred structures for the (R² ₂A)_(m) bridging group are Si(CH₃)₂,SiPh₂, CH₂CH₂, the Si(CH₃)₂ being the most preferred.

Non limitative examples of compound of formula (I) are:

as well as the corresponding dihydride and dimethyl compounds.

Preferably the compounds of formula (I) have formula (III):

(III)wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, A, M, T, X and m are defined asabove.

Metallocene compounds of formula (I) or (III) are well known in the art,they can be prepared according to known procedure, such as thosedescribed in WO 01/44318 and U.S. Pat. No. 5,786,432. Alumoxanes used ascomponent b) can be obtained by reacting water with an organo-aluminiumcompound of formula H_(j)AlU_(3-j) or H_(j)Al₂U_(6-j), where Usubstituents, same or different, are hydrogen atoms, C₁-C₂₀-alkyl,C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl,optionally containing silicon or germanium atoms with the proviso thatat least one U is different from halogen, and j ranges from 0 to 1,being also a non-integer number. In this reaction the molar ratio ofAl/water is preferably comprised between 1:1 and 100:1. The molar ratiobetween aluminium and the metal of the metallocene is comprised betweenabout 10:1 and about 20000:1, and more preferably between about 100:1and about 5000:1.

The alumoxanes used in the catalyst according to the invention areconsidered to be linear, branched or cyclic compounds containing atleast one group of the type:

wherein the substituents U, same or different, are described above.

In particular, alumoxanes of the formula:

can be used in the case of linear compounds, wherein n¹ is 0 or aninteger from 1 to 40 and the substituents U are defined as above, oralumoxanes of the formula:

can be used in the case of cyclic compounds, wherein n² is an integerfrom 2 to 40 and the U substituents are defined as above. Examples ofalumoxanes suitable for use according to the present invention aremethylalumoxane (MAO), tetra-(isobutyl)alumoxane (TIBAO),tetra-(2,4,4-trimethyl-pentyl)alumoxane (TIOAO),tetra-(2,3-dimethylbutyl)alumoxane (TDMBAO) andtetra-(2,3,3-trimethylbutyl)alumoxane (TTMBAO). Particularly interestingcocatalysts are those described in WO 99/21899 and in PCT/EP00/09111 inwhich the alkyl and aryl groups have specific branched patterns.Non-limiting examples of aluminium compounds according to saidinternational applications are:

-   tris(2,3,3-trimethyl-butyl)aluminium,    tris(2,3-dimethyl-hexyl)aluminium,    tris(2,3-dimethyl-butyl)aluminium,    tris(2,3-dimethyl-pentyl)aluminium,    tris(2,3-dimethyl-heptyl)aluminium,    tris(2-methyl-3-ethyl-pentyl)aluminium,    tris(2-methyl-3-ethyl-hexyl)aluminium,    tris(2-methyl-3-ethyl-heptyl)aluminium,    tris(2-methyl-3-propyl-hexyl)aluminium,    tris(2-ethyl-3-methyl-butyl)aluminium,    tris(2-ethyl-3-methyl-pentyl)aluminium,    tris(2,3-diethyl-pentyl)aluminium,    tris(2-propyl-3-methyl-butyl)aluminium,    tris(2-isopropyl-3-methyl-butyl)aluminium,    tris(2-isobutyl-3-methyl-pentyl)aluminium,    tris(2,3,3-trimethyl-pentyl)aluminium,    tris(2,3,3-trimethyl-hexyl)aluminium,    tris(2-ethyl-3,3-dimethyl-butyl)aluminium,    tris(2-ethyl-3,3-dimethyl-pentyl)aluminium,    tris(2-isopropyl-3,3-dimethyl-butyl)aluminium,    tris(2-trimethylsilyl-propyl)aluminium,    tris(2-methyl-3-phenyl-butyl)aluminium,    tris(2-ethyl-3-phenyl-butyl)aluminium,    tris(2,3-dimethyl-3-phenyl-butyl)aluminium,    tris(2-phenyl-propyl)aluminium,    tris[2-(4-fluoro-phenyl)-propyl]aluminium,    tris[2-(4-chloro-phenyl)-propyl]aluminium,    tris[2-(3-isopropyl-phenyl)-propyl]aluminium,    tris(2-phenyl-butyl)aluminium,    tris(3-methyl-2-phenyl-butyl)aluminium,    tris(2-phenyl-pentyl)aluminium,    tris[2-(pentafluorophenyl)-propyl]aluminium,    tris[2,2-diphenyl-ethyl]aluminium and    tris[2-phenyl-2-methyl-propyl]aluminium, as well as the    corresponding compounds wherein one of the hydrocarbyl groups is    replaced with a hydrogen atom, and those wherein one or two of the    hydrocarbyl groups are replaced with an isobutyl group. Amongst the    above aluminium compounds, trimethylaluminium (TMA),    triisobutylaluminium (TIBAL), tris(2,4,4-trimethyl-pentyl)aluminium    (TIOA), tris(2,3-dimethylbutyl)aluminium (TDMBA) and    tris(2,3,3-trimethylbutyl)aluminium (TTMBA) are preferred.    Non-limiting examples of compounds able to form an alkylmetallocene    cation are compounds of formula D⁺E⁻, wherein D⁺ is a Brønsted acid,    able to donate a proton and to react irreversibly with a substituent    X of the metallocene of formula (I) and E⁻ is a compatible anion,    which is able to stabilize the active catalytic species originating    from the reaction of the two compounds, and which is sufficiently    labile to be able to be removed by an olefinic monomer. Preferably,    the anion E⁻ comprises of one or more boron atoms. More preferably,    the anion E⁻ is an anion of the formula BAr₄ ⁽⁻⁾, wherein the    substituents Ar which can be identical or different are aryl    radicals such as phenyl, pentafluorophenyl or    bis(trifluoromethyl)phenyl. Tetrakis-pentafluorophenyl borate is    particularly preferred examples of these compounds are described in    WO 91/02012. Moreover, compounds of the formula BAr₃ can    conveniently be used. Compounds of this type are described, for    example, in the published International patent application WO    92/00333. Other examples of compounds able to form an    alkylmetallocene cation are compounds of formula BAR₃P wherein P is    a substituted or unsubstituted pyrrol radicals. These compounds are    described in PCT/EP01/01467. all these compounds containing boron    atoms can be used in a molar ratio between boron and the metal of    the metallocene comprised between about 1:1 and about 10:1;    preferably 1:1 and 2.1; more preferably about 1:1.

Non limiting examples of compounds of formula D⁺E⁻ are:

-   Triethylammoniumtetra(phenyl)borate,-   Tributylammoniumtetra(phenyl)borate,-   Trimethylammoniumtetra(tolyl)borate,-   Tributylammoniumtetra(tolyl)borate,-   Tributylammoniumtetra(pentafluorophenyl)borate,-   Tributylammoniumtetra(pentafluorophenyl)aluminate,-   Tripropylammoniumtetra(dimethylphenyl)borate,-   Tributylammoniumtetra(trifluoromethylphenyl)borate,-   Tributylammoniumtetra(4-fluorophenyl)borate,-   N,N-Dimethylaniliniumtetra(phenyl)borate,-   N,N-Diethylaniliniumtetra(phenyl)borate,-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)borate,-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)aluminate,-   Di(propyl)ammoniumtetrakis(pentafluorophenyl)borate,-   Di(cyclohexyl)ammoniumtetrakis(pentafluorophenyl)borate,-   Triphenylphosphoniumtetrakis(phenyl)borate,-   Triethylphosphoniumtetrakis(phenyl)borate,-   Diphenylphosphoniumtetrakis(phenyl)borate,-   Tri(methylphenyl)phosphoniumtetrakis(phenyl)borate,-   Tri(dimethylphenyl)phosphoniumtetrakis(phenyl)borate,-   Triphenylcarbeniumtetrakis(pentafluorophenyl)borate,-   Triphenylcarbeniumtetrakis(pentafluorophenyl)aluminate,-   Triphenylcarbeniumtetrakis(phenyl)aluminate,-   Ferroceniumtetrakis(pentafluorophenyl)borate,-   Ferroceniumtetrakis(pentafluorophenyl)aluminate.-   Triphenylcarbeniumtetrakis(pentafluorophenyl)borate,-   N,N-Dimethylaniliniumtetrakis(pentafluorophenyl)borate.

Further compounds that can be used are those of formula RM′—O—M′R, Rbeing an alkyl or aryl group, and M′ is selected from an element of theGroup 13 of the Periodic Table of the Elements (new IUPAC version).Compounds of this type are described, for example, in the Internationalpatent application WO 99/40129. Organic aluminum compounds used ascompound c) are those of formula H_(j)AlU_(3-j) or H_(j)Al₂U_(6-j)described above. The polymerization process of the present invention canbe carried out in liquid phase, optionally in the presence of an inerthydrocarbon solvent, or in gas phase. Said hydrocarbon solvent can beeither aromatic (such as toluene) or aliphatic (such as propane, hexane,heptane, isobutane, cyclohexane and 2,2,4-trimethylpentane). Preferablythe polymerization is carried out in liquid monomer. The polymerizationtemperature preferably ranges from 0° C. to 250° C.; preferablycomprised between 20° C. and 150° C. and, more particularly between 40°C. and 90° C.; The molecular weight distribution of the polymer obtainedwith the process of the present invention can be varied by usingmixtures of different metallocene compounds or mixtures of themetallocene compound of formula (I) and a Ziegler-Natta catalyst or bycarrying out the polymerization in several stages at differentpolymerization temperatures and/or different concentrations of themolecular weight regulators and/or different monomer concentration. Thepolymerization yield depends on the purity of the transition metalorganometallic catalyst compound a) in the catalyst, therefore, saidcompound can be used as such or can be subjected to purificationtreatments before use. With the process of the present invention1-butene can be polymerized with high yields and the isotactic polymersobtained show a high molecular weight and a low content of regioerrors,i.e. 4.1 insertions. Moreover the obtained polymer show very high valuesof the flexural modulus allowing to obtain pipes having a longerdurability and thinner walls. Therefore another object of the presentinvention is a 1-butene homopolymer having the followingcharacteristics:

-   -   intrinsic viscosity (I.V.)>0.7 dL/g; preferably >1 dL/g; more        preferably >1.5 dL/g;    -   isotactic triads (mm)>70%; preferably >95%; more preferably        >98%;    -   a flexural modulus (ASTM D 638)>400 Mpa; preferably >425 MPa;        more preferably >450 Mpa;    -   melting point >105° C., preferably >108° C.; more        preferably >110° C.

The 4.1 insertions are lower than <0.90%; preferably the 4.1 insertionsare comprised between 0.05% and 0.90%; more preferably they arecomprised between 0.10% and 0.70%; a further preferred range is between0.10% and 0.39%.

Preferably the 1-butene homopolymers of the invention have molecularweight distribution (Mw/Mn)<3; more preferably <2.5; even morepreferably <2.2.

When 1-butene is copolymerized with ethylene, propylene or an alphaolefin of formula CH₂═CHZ wherein Z is a C₃-C₁₀ alkyl group, a copolymerhaving a comonomer derived units content from 0 to 50% by weight can beobtained. preferably from 0.5 to 20% by weight. Preferred comonomers areethylene or propylene.

A particular interesting copolymer that can be obtained with the processof the present invention is a 1-butene/ethylene copolymer having acontent of ethylene derived units from 0.1% to 5% by weight preferablyfrom 0.5% to 2.5% by weight in which the ethylene content in the polymer(C₂) and the melting point of the polymer (Tm) meet the followingrelation:Tm<−0.3283C₂ ³+4.7184C₂ ²−22.454C₂+114.

Preferably the relation is Tm<−0.3283C₂ ³+4.7184C₂ ²−22.454C₂+113; morepreferably Tm<−0.3283C₂ ³+4.7184C₂ ²−22.454C₂+111.2.

When the content of ethylene derived units in the above copolymer rangesfrom 0.1 to 2.5% by weight the ethylene content in the polymer (C₂) andthe melting point of the polymer (Tm) meet the following relation:Tm=4.0037C₂ ²−21.91C₂+114;preferably the relation is Tm=4.0037C₂ ²−21.91C₂+113; more preferablyTm=4.0037C₂ ²−21.91C₂+110.5.

Furthermore the 1-butene/ethylene copolymer above described are endowedwith a molecular weight distribution (Mw/Mn)<4.

A further feature of said 1-butene/ethylene copolymer is the intrinsicviscosity (I.V.)>0.7 dL/g; preferably >1 dL/g.

EXPERIMENTAL SECTION

The intrinsic viscosity (I.V.) was measured in tetrahydronaphtalene(THN) at 135° C.

The melting points of the polymers (T_(m)) were measured by DifferentialScanning Calorimetry (D.S.C.) on a Perkin Elmer DSC-7 instrument,according to the standard method. A weighted sample (5-10 mg) obtainedfrom the polymerization was sealed into aluminum pans and heated at 180°C. with a scanning speed corresponding to 10° C./minute. The sample waskept at 180° C. for 5 minutes to allow a complete melting of all thecrystallites. Successively, after cooling to 20° C. with a scanningspeed corresponding to 10° C./minute. After standing 2 minutes at 20°C., the sample was heated for the second time at 180° C. with a scanningspeed corresponding to 10° C./min. In this second heating run, the peaktemperature was taken as the melting temperature (T_(m)) and the area asglobal melting enthalpy (ΔH_(f)).

The molecular weight distribution was determined on a WATERS 150 C usingthe following chromatographic conditions:

Columns: 3x SHODEX AT 806 MS; 1x SHODEX UT 807; 1x SHODEX AT-G; Solvent:1,2,4 trichlorobenzene (+0.025% 2,6-Di-tert.Butyl-4- Methyl-Phenol);Flow rate: 0.6-1 ml/min; Temperature: 135° C.; Detector: INFRARED AT λ ≅3.5 μm; Calibration: Universal Calibration with PS-Standards.

¹³C-NMR spectra were acquired on a DPX-400 spectrometer operating at100.61 MHz in the Fourier transform mode at 120° C. The peak of the 2B₂carbon (nomenclature according to Carman, C. J.; Harrington, R. A.;Wilkes, C. E. Macromolecules 1977, 10, 535) was used as internalreference at 27.73. The samples were dissolved in1,1,2,2-tetrachloroethane-d2 at 120° C. with a 8% wt/v concentration.Each spectrum was acquired with a 90° pulse, 15 seconds of delay betweenpulses and CPD (waltz16) to remove 1H-13C coupling. About 3000transients were stored in 32K data points using a spectral window of6000 Hz. Assignments of 4.1 insertion were made according to Busico (V.Busico, R. Cipullo, A. Borriello, Macromol. Rapid. Commun. 1995, 16,269-274)

Chemical Shift (ppm) Carbon Sequence 40.21 CH₂ (S_(αα)) B 39.65 CH₂ D137.3  CH D2 34.99 CH B 34.31 CH₂ D3 31.13 CH₂ D5 27.73 CH₂ branch B mmmm27.57 CH₂ branch B mmmr 27.37 CH₂ branch B mmrr 27.21-27.14 CH₂ D4 + D626.57 CH₂ branch B mrrm 10.96 CH₃ B

The content of 4.1 insertions was calculated as follows: 4.1units=0.5×I₄×100/(I₂+I₄)

Preparation of Catalyst Components

Racdimethylsilandiylbis-6-[2,5-dimethyl-3-(2′-methyl-phenyl)cyclopentadienyl-[1,2-b]-thiophene]zirconiumdichloride (A-1), racdimethylsilandiylbis-6-[2,5-dimethyl-3-(2′,5′-dimethyl-phenyl)cyclopentadienyl-[1,2-b]-thiophene]zirconiumdichloride (A-2) and racdimethylsilandiylbis-6-(2,5-dimethyl-3-phenylcyclopentadienyl-[1,2-b]-thiophene)zirconiumdichloride (A-3) were prepared according to PCT/EP00/12406. Racdimethylsilylbis(2-methyl-4-phenyl-indenyl) zirconium dichloride (A-4)was prepared according to U.S. Pat. No. 5,786,432. The cocatalystmethylalumoxane (MAO) was a commercial product which was used asreceived (Witco AG, 10% wt/vol toluene solution, 1.7 M in Al).

Examples 1-4 and Comparative Examples 5-6 1-butene homopolymer

The catalyst mixture was prepared by dissolving the amount of themetallocene indicated in table 1 in 8 ml of toluene (excepting forexample 3 in which 3 ml of toluene has been used) with the proper amountof the MAO solution (amounts are reported in table 1), obtaining asolution which was stirred for 10 min at room temperature before beinginjected into the autoclave. 4 mmol of Al(i-Bu)₃ (TIBA) (as a 1 Msolution in hexane) and 712 g of 1-butene were charged, at roomtemperature, in a 2.3-L jacketed stainless-steel autoclave, equippedwith magnetically driven stirrer and a 35-mL stainless-steel vial,connected to a thermostat for temperature control. The autoclave wasthen thermostatted at 2° C. below the polymerization temperature and thecatalyst system, prepared as reported above, was injected in theautoclave by means of nitrogen pressure through the stainless-steelvial. The temperature was rapidly raised to the polymerizationtemperature and the polymerization was carried out at constanttemperature, for a time indicated in table 1. After cooling the reactorto room temperature, the polymer was dried under reduced pressure, at60° C. The polymerization conditions and the characterization data ofthe obtained polymers are reported in Table 1.

Examples 7-13 1-butene homopolymer

The catalyst mixture was prepared by dissolving the amount of themetallocene indicated in table 2 in 8 ml of toluene with the properamount of the MAO solution (Al/Zr ratio reported in table 2), obtaininga solution which was stirred for 10 min at room temperature before beinginjected into the autoclave. A 4.25 litres steel autoclave, equippedwith magnetically stirred anchor (usual stirring rate 550 rpm) and withdifferent Flow Record & Control systems (FRC), among which a FRC havingmaximum flow rate of 9000 gr/hour for 1-butene and two FRC havingmaximum flow rate of 500 and 30 g/h for ethylene is cleaned with warmnitrogen (1.5 barg N2, 70° C., 1 hour). After the above mentionedautoclave cleaning, the stirring starts and 1-butene is fed into thereactor (1350 gr at 30° C.) together with 6 mmol of Al(i-Bu)₃ (TIBA) (asa 1 M solution in hexane). Subsequently, the reactor inner temperatureis raised from 30° C. to the polymerisation temperature (indicated intable 2); as a consequence the pressure increases. When pressure andtemperature are constant, the catalytic solution is fed into the reactorwith a nitrogen overpressure. The polymerisation is run for a timeindicated in table 2 at the chosen polymerization temperature. Then thestirring is interrupted; the pressure into the autoclave is raised to 20bar-g with nitrogen. The bottom discharge valve is opened and the1-butene/poly-1-butene mixture is discharged into the steel heated tankcontaining water at 70° C. The tank heating is switched off and a fluxof 0.5 bar-g nitrogen is fed. After 1 hour cooling at room temperaturethe steel tank is opened and the wet polymer collected. The wet polymeris dried in oven under nitrogen at 70° C. The polymerization conditionsand the characterization data of the obtained polymers are reported inTable 2.

Characterization of Homopolymer

Samples of polymer obtained from examples 3, 7, 9, and 10 were ground inan electric mill with liquid nitrogen in order to achieve the right sizeto feed them in a Brabender® mixer chamber. The ground samples weremixed in a Brabender® chamber with 1% 2,6-di-t-butyl-4-methyl phenol(BHT) at 200° C. and then transformed in 1.9 and 4.0 mm thick plaquesthrough compression molding at 200° C.

The 1.9 mm thick plaques were submitted to tensile test (according toASTM D 638 method), while the 4.0 mm thick plaques were submitted to theflexural modulus determination according to ISO 178 method. The resultsare reported in table 2a.

Examples 14-19 1-butene/ethylene copolymer

The catalyst mixture was prepared by dissolving the amount of themetallocene indicated in table 2 in toluene with the proper amount ofthe MAO solution (Al/Zr=10000), obtaining a solution which was stirredfor 10 min at room temperature before being injected into the autoclave.A 4.25 litres steel autoclave, equipped with magnetically stirred anchor(usual stirring rate 550 rpm) and with the proper Flow Record & Controlsystems (FRC), among which a FRC having maximum flow rate of 9000gr/hour for 1-butene and two FRC having maximum flow rate of 500 and 30g/h for ethylene is cleaned with warm nitrogen (1.5 barg N₂, 70° C., 1hour). After the above mentioned autoclave cleaning, the stirringstarts, 1-butene is fed into the reactor (1350 gr at 30° C. exceptingfor example 10 wherein 1368 g of 1-butene are used) with the amount ofethylene reported in table 3, together with 6 mmol of Al(i-Bu)₃ (TIBA)(as a 1 M solution in hexane). Subsequently, the reactor innertemperature is raised from 30° C. to the polymerisation temperature(indicated in table 3); as a consequence the pressure increases. Whenpressure and temperature are constant, the catalytic solution is fedinto the reactor with a nitrogen overpressure and the polymerisationpressure is kept constant feeding only ethylene (amount indicated intable 3). The polymerisation is run for a time indicated in table 3 atthe chosen polymerization temperature. Then the stirring is interrupted;the pressure into the autoclave is raised to 20 bar-g with nitrogen. Thebottom discharge valve is opened and the 1-butene/poly-1-butene mixtureis discharged into the steel heated tank containing water at 70° C. Thetank heating is switched off and a flux of 0.5 bar-g nitrogen is fed.After 1 hour cooling at room temperature the steel tank is opened andthe wet polymer collected. The wet polymer is dried in a oven undernitrogen at 70° C. The polymerization conditions and thecharacterization data of the obtained polymers are reported in Table 3

TABLE 1 regioerrors T_(pol) t Yield Activity I.V. triads % 4,1 T_(m)(II)ΔH_(f)(II) Ex metall. Mg Al_((MAO))/Zr ° C. (min) (g) kg/(g_(cat)*h)(dL/g) M_(w)/M_(n) (mm) insertions ° C. J/g 1 A-1 2 1000 60 17 73.8130.2 1.8 n.a.  >99 0.17%  110 40 2 A-1 3 200 60 30 89.9 60.0 2.0 n.a.≈100 0.3% n.a. n.a. 3 A-2 1 1000 60 60 69.9 69.9 1.7 2.16 ≈100 0.2% 11134 4 A-2 3 200 70 30 124.9 83.3 1.3 n.a. n.a. n.a. n.a. n.a.  5* A-3 41000 60 30 96.5 48.3 1.0 2.12 ≈100   1% 100 37  6* A-4 4 1000 60 60 39.59.9 0.9 n.a. ≈100 0.4% 105 33 *comparative n.a. = not available

TABLE 2 t Yield Activity I.V. T_(m)(II) ΔH_(f)(II) Ex Metall. MgAl_((MAO))/Zr T_(pol) (min) (g) Kg/(g_(cat)*h) (dL/g) M_(w)/M_(n) ° C.J/g 7 A-2 3 1000 50 43 263 122.3 2.31 2.09 111.6 36.0 8 A-2 1 1000 70 60130 130.0 1.50 2.18 109.2 35.4 9 A-2 1 1000 85 60 195 195.0 n.a. 2.12n.a. n.a. 10 A-1 3 1000 50 53 285 107.5 2.72 2.14 110.2 34.9 11 A-1 21000 85 60 90 45.0 n.a. 2.12 n.a. n.a. 12 A-1 2 1000 85 60 312.4 156.2n.a. 2.18 n.a. n.a. 13 A-1 2 500 85 60 166 83.0 n.a. 2.16 n.a. n.a.

TABLE 2a Flexural Yield Break Elongation modulus strength strength atbreak Ex (MPa) (MPa) (MPa) (%) 3 480 n.a. n.a. n.a. 7 472 19.2 40.0 3009 472 23.8 22.8 218 10 437 18.6 37.9 280 n.a. = not available

TABLE 3 C₂ T_(pol) t added C₂ feed Yield Activity C₂ wt % T_(m)(II) Exmet. mg ° C. (min) g g (g) kg/ (g_(cat)*h) I.V. (IR) M_(w)/M_(n) ° C. 14A-1 1 70 70 0.9 4 224.0 192.0 1.22 0.50 2.41 99.56 15 A-1 1 70 70 0.8 6127.0 108.9 1.26 0.50 2.40 99.72 16 A-1 1 70 70 2.6 17 432.0 370.3 1.091.90 2.68 78.90 17 A-2 1 70 70 1.1 0.4 96.0 82.3 1.17 0.70 2.52 96.02 18A-2 1 70 70 2.3 4.6 203.0 174.0 1.41 2.20 3.92 81.00 19 A-2 1 70 70 3.017 340.0 291.4 1.17 1.70 2.91 83.84 C₂ added = ethylene added in thereactor with 1-butene C₂ feed = ethylene feed during the polymerization

1. A 1-butene/ethylene copolymer having a content of ethylene derivedunits from 0.1% to 2.5% by weight in which an ethylene content in thepolymer (C₂) and a melting point of the polymer (Tm) meet the followingrelation:Tm=4.0037C₂ ²−21.91C₂+114.
 2. A 1-butene/ethylene copolymer produced bya process comprising the step of contacting under polymerizationconditions 1-butene and up to 20% by mol of ethylene and optionally atleast one of propylene and an alpha olefin of formula CH₂═CHZ wherein Zis a C₃-C₁₀ alkyl group, in the presence of a catalyst system obtainedby contacting: a) a racemic or racemic-like bridged metallocene compoundof formula (I)

wherein R¹, same or different, is hydrogen, a linear or branchedsaturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical, optionally containingheteroatoms belonging to groups 13-17 of the Periodic Table of theElements; A, same or different, is a carbon atom, a germanium atom or asilicon atom; with the proviso that when m is 1, A is different from acarbon atom; m is 1 or 2; R², same or different, is hydrogen, a linearor branched saturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical, optionallycontaining heteroatoms belonging to groups 13-17 of the Periodic Tableof the Elements; M is a transition metal atom selected from thosebelonging to group 4 of the Periodic Table of the Elements (IUPACversion); X, same or different, is a hydrogen atom, a halogen atom, or aR, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ group, wherein R is a linear orbranched, saturated or unsaturated C₁-C₂₀ alkyl, C₃-C₂₀ cycloalkyl,C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl or C₇-C₂₀ arylalkyl radical, optionallycontaining heteroatoms belonging to groups 13-17 of the Periodic Tableof the Elements; or two X can optionally form a substituted orunsubstituted butadienyl radical or a OR¹¹O group wherein R¹¹ is adivalent radical selected from C₁-C₂₀ alkylidene, C₆-C₄₀ arylidene,C₇-C₄₀ alkylarylidene and C₇-C₄₀ arylalkylidene radicals; L, same ordifferent, is a moiety of formula (IIa), (IIb), or (IIc)

wherein in the moiety of formula (IIa), T bonds to the cyclopentadienylgroup in position 5; in the moiety of formula (IIb), N bonds to thecyclopentadienyl group in position 4; in the moiety of formula (IIc),the carbon atom marked with the symbol * bonds to the cyclopentadienylgroup in position 4; T is an oxygen (O) atom or a sulphur (S) atom or aCH₂ group; R³ is hydrogen, a linear or branched saturated or unsaturatedC₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl,C₇-C₂₀-arylalkyl radical, optionally containing heteroatoms belonging togroups 13-17 of the Periodic Table of the Elements; R⁴ is a linear orbranched saturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical, optionallycontaining heteroatoms belonging to groups 13-17 of the Periodic Tableof the Elements; R⁵, R⁶, R⁷, R⁸ and R⁹ same or different are selectedfrom the group consisting of hydrogen, linear or branched saturated orunsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl, and C₇-C₂₀-arylalkyl radical, optionally containingheteroatoms belonging to groups 13-17 of the Periodic Table of theElements or two adjacent groups can form together a saturated orunsaturated condensed 5 or 6 membered ring optionally containingheteroatoms belonging to groups 13-16 of the Periodic Table of theElements; b) an alumoxane or a compound that forms an alkylmetallocenecation; and c) optionally an organo aluminum compound; the1-butene/ethylene copolymer having a content of ethylene derived unitsfrom 0.1% to 5.0% by weight in which an ethylene content in the polymer(C₂) and a melting point of the polymer (Tm) meet the followingrelation:Tm<−0.3283C₂ ³+4.7184C₂ ²−22.454C₂+114.
 3. A 1-butene/ethylene copolymerproduced by a process comprising the step of contacting underpolymerization conditions 1-butene and up to 20% by mol, of ethylene andat least one of propylene and an alpha olefin of formula CH₂═CHZ whereinZ is a C₃-C₁₀ alkyl group, in the presence of a catalyst system obtainedby contacting: a) a racemic or racemic-like bridged metallocene compoundof formula (I)

wherein R¹, same or different, is hydrogen, a linear or branchedsaturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical, optionally containingheteroatoms belonging to groups 13-17 of the Periodic Table of theElements; A, same or different, is a carbon atom, a germanium atom or asilicon atom; with the proviso that when m is 1, A is different from acarbon atom; m is 1 or 2; R², same or different, is hydrogen, a linearor branched saturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical, optionallycontaining heteroatoms belonging to groups 13-17 of the Periodic Tableof the Elements; M is a transition metal atom selected from thosebelonging to group 4 of the Periodic Table of the Elements (IUPACversion); X, same or different, is a hydrogen atom, a halogen atom, or aR, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ group, wherein R is a linear orbranched, saturated or unsaturated C₁-C₂₀ alkyl, C₃-C₂₀ cycloalkyl,C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl or C₇-C₂₀ arylalkyl radical, optionallycontaining heteroatoms belonging to groups 13-17 of the Periodic Tableof the Elements; or two X can optionally form a substituted orunsubstituted butadienyl radical or a OR¹¹O group wherein R¹¹ is adivalent radical selected from C₁-C₂₀ alkylidene, C₆-C₄₀ arylidene,C₇-C₄₀ alkylarylidene and C₇-C₄₀ arylalkylidene radicals; L, same ordifferent, is a moiety of formula (IIa), (IIb), or (IIc)

wherein in the moiety of formula (IIa), T bonds to the cyclopentadienylgroup in position 5; in the moiety of formula (IIb), N bonds to thecyclopentadienyl group in position 4; in the moiety of formula (IIc),the carbon atom marked with the symbol * bonds to the cyclopentadienylgroup in position 4; T is an oxygen (O) atom or a sulphur (S) atom or aCH₂ group; R³ is hydrogen, a linear or branched saturated or unsaturatedC₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl,C₇-C₂₀-arylalkyl radical, optionally containing heteroatoms belonging togroups 13-17 of the Periodic Table of the Elements; R⁴ is a linear orbranched saturated or unsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl,C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl, C₇-C₂₀-arylalkyl radical, optionallycontaining heteroatoms belonging to groups 13-17 of the Periodic Tableof the Elements; R⁵, R⁶, R⁷, R⁸ and R⁹ same or different are selectedfrom the group consisting of hydrogen, linear or branched saturated orunsaturated C₁-C₂₀-alkyl, C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl,C₇-C₂₀-alkylaryl, and C₇-C₂₀-arylalkyl radical, optionally containingheteroatoms belonging to groups 13-17 of the Periodic Table of theElements or two adjacent groups can form together a saturated orunsaturated condensed 5 or 6 membered ring optionally containingheteroatoms belonging to groups 13-16 of the Periodic Table of theElements; b) an alumoxane or a compound that forms an alkylmetallocenecation; and c) optionally an organo aluminum compound; the1-butene/ethylene copolymer having a content of ethylene derived unitsfrom 0.1% to 2.5% by weight in which an ethylene content in the polymer(C₂) and a melting point of the polymer (Tm) meet the followingrelation:Tm=4.0037C₂ ²−21.91C₂+114.